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Abstract:

A finishing system for finishing a part using a robot may include a
staging fixture, a gripper, and a regrip fixture. The part may include an
inner surface, a protrusion, and a notch. The staging fixture may include
first pads adapted to engage the protrusion. The gripper may be adapted
to couple to the robot and may include a first outer surface and second
pads. The first outer surface may be shaped to engage the inner surface
of the part and the second pads may be adapted to clamp the protrusion on
the part. The regrip fixture may include a tab adapted to engage the
notch.

Claims:

1. A gripper for finishing a part using a robot, the part including
fingers and a gap between the fingers, each of the fingers having an
inner surface with a protrusion extending from the inner surface, the
gripper comprising: a support including a first bore, an opening, and an
outer surface, the first bore extending at least partially through the
support along a length thereof, the opening extending at least partially
through the support normal to the first bore, and the outer surface being
shaped to substantially conform to the inner surface of the part; a first
pad and a second pad disposed within the first bore and including
opposing clamp surfaces, the clamp surfaces being exposed through the
opening and shaped to substantially conform to the protrusion on the
part; and a pushrod disposed within the first bore and adapted to couple
the first pad to an actuator, the pushrod being slideable within the
first bore to actuate the first pad relative to the second pad and to
selectively clamp the protrusion on the part between the first pad and
the second pad with the clamp surfaces.

2. The gripper of claim 1, wherein the outer surface of the support
engages the inner surface of one of the fingers without extending across
the gap between the fingers when the protrusion on the part is clamped
between the first pad and the second pad.

3. The gripper of claim 1, wherein the part is a femoral knee implant,
the fingers are condyles, the gap is a cruciate gap, and the protrusion
is a post.

4. The gripper of claim 1, wherein the support includes an enclosed end,
the second pad being disposed adjacent to and attached to the enclosed
end.

5. The gripper of claim 1, further comprising the actuator and a first
adapter configured to couple the actuator to the robot.

6. The gripper of claim 5, further comprising a second adapter coupling
the support to the actuator and including a second bore coaxially aligned
with the first bore in the support.

7. The gripper of claim 6, wherein the actuator is a pneumatic cylinder
including a piston, the piston including a cavity coaxially aligned with
the first bore in the support and receiving the pushrod therein.

8. The gripper of claim 7, wherein the pushrod includes outer threads
engaging inner threads of the piston, and a nut is threaded onto the
outer threads of the pushrod and abutting the piston, the nut preventing
relative movement between the pushrod and the piston.

9. The gripper of claim 1, wherein the outer surface extends around a
perimeter of the support and the opening extends through the support such
that the gripper is adapted to receive the protrusion at opposite ends of
the opening.

10. The gripper of claim 1, wherein the support includes a flat surface
opposite the outer surface and the opening extends only partially through
the support.

11. The gripper of claim 1, wherein the protrusion is cylindrical and the
clamp surfaces each include a semi-circular profile conforming to the
protrusion.

12. The gripper of claim 1, wherein the outer surface includes a first
surface, a second surface that is oriented at a reflex angle relative to
the first surface, and a third surface that is oriented at a right angle
relative to the first surface.

13. A finishing system for finishing a part using a robot, the part
including an inner surface, a protrusion, and a notch, the robotic
finishing system comprising: a staging fixture including first pads
adapted to engage the protrusion; a gripper adapted to couple to the
robot and including a first outer surface and second pads, the first
outer surface being shaped to engage the inner surface of the part, the
second pads being adapted to clamp the protrusion on the part; and a
regrip fixture including a tab adapted to engage the notch.

14. The finishing system of claim 13, wherein the first outer surface of
the gripper engages the inner surface of the part when the second pads
clamp the protrusion on the part.

15. The finishing system of claim 13, wherein the first outer surface of
the gripper substantially conforms to the inner surface of the part.

16. The finishing system of claim 13, wherein the staging fixture
includes a first coupler adapted to couple one of the first pads to a
first actuator.

17. The finishing system of claim 13, wherein the gripper includes a
second coupler adapted to couple one of the second pads to a second
actuator.

18. The finishing system of claim 13, wherein the staging fixture
includes an actuator, a coupler, and a support, the support housing the
first pads, the coupler coupling the support to the actuator, and the
actuator being operable to actuate one of the first pads and thereby
clamp the protrusion of the part between the first pads.

19. The finishing system of claim 18, wherein the support is configured
to avoid contacting the part when the first pads engage the protrusion on
the part.

20. The finishing system of claim 13, wherein the staging fixture
includes a proximity sensor that detects a presence of the protrusion
between the first pads.

21. The finishing system of claim 13, wherein the regrip fixture includes
an actuator, a coupler, and a finger including the tab, the coupler
coupling the finger to the actuator, and the actuator being operable to
insert the tab into the notch.

[0004] An important aspect of robotic finishing knee implants is the need
to manipulate the implant to expose all surfaces to a finishing device
such as a wheel or belt. To accomplish this, the implant must be held by
the robot and maneuvered to various orientations relative to the
finishing device. Importantly, the robot must hold the implant against
the finishing device with pressure without marring the surface of the
implant when picking it up or putting it down.

[0005] One technique for enabling a knee implant to be picked up and
manipulated by a robot in a finishing operation is to mount the knee
implant to a metal support bar. In this technique, the knee implant is
fixed to a central region of a metal bar through the use of fasteners
such as screws. The bar laterally extends beyond the both outboard edges
of the knee implant to provide two graspable handles for the robot. The
robot may then use jaws to clamp onto one handle of the bar and
manipulate the knee implant relative to the finishing device. The knee
implant and bar assembly may then be set down while the robot repositions
its jaws to the other graspable handle of the bar. The knee implant may
then be further manipulated relative to the finishing device. Mounting a
knee implant to a support bar is labor intensive and involves significant
costs associated with the support bars.

[0006] A second technique for enabling robotic manipulation of a knee
implant is to secure a gripper to a robot having jaws. The gripper allows
the robot to directly clamp the knee implant via actuation of the jaws.
One type of a conventional gripper includes two opposing clamp bars that
clamp onto two posts extending from an inner surface of the knee implant.
The robot positions the clamp bars normal to the outboard edges of the
knee implant on opposite sides of the two posts, and then brings the
clamp bars together to clamp the posts. The robot closes its jaws to
bring the clamp bars together and opens its jaws to move the clamp
members apart. When clamping the posts, the clamp bars extend across a
cruciate gap separating two condyles of the knee implant from which the
two posts extend. Using a gripper such as the one described above for
finishing knee implants requires manually finishing the cruciate gap
obstructed by the clamp bars during automated finishing.

[0007] Thus, there is a need for a finishing system that enables the
direct clamping of knee implants while providing maximized part
clearance.

SUMMARY

[0008] This section provides a general summary of the disclosure, and is
not a comprehensive disclosure of its full scope or all of its features.

[0009] A finishing system for finishing a part using a robot may include a
staging fixture, a gripper, and a regrip fixture. The part may include an
inner surface, a protrusion, and a notch. The staging fixture may include
first pads adapted to engage the protrusion. The gripper may be adapted
to couple to the robot and may include a first outer surface and second
pads. The first outer surface may be shaped to engage the inner surface
of the part and the second pads may be adapted to clamp the protrusion on
the part. The regrip fixture may include a tab adapted to engage the
notch.

[0010] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples in
this summary are intended for purposes of illustration only and are not
intended to limit the scope of the present disclosure.

DRAWINGS

[0011] The drawings described herein are for illustrative purposes only of
selected embodiments and not all possible implementations, and are not
intended to limit the scope of the present disclosure.

[0012] FIG. 1 is a plan view of a robotic finishing system according to
the principles of the present disclosure;

[0013] FIG. 2 is a perspective view of a part staging fixture according to
the principles of the present disclosure supporting a knee implant;

[0014] FIG. 3 is a planar view of the part staging fixture of FIG. 2
supporting a knee implant;

[0015] FIG. 4 is a perspective view of a direct clamp gripper according to
the principles of the present disclosure clamping a post of a knee
implant;

[0016] FIG. 5 is a perspective view of the direct clamp gripper of FIG. 4
and a knee implant, with the gripper clamping a different post of the
knee implant;

[0017] FIG. 6 is an exploded perspective view of the direct clamp gripper
of FIG. 4;

[0018] FIG. 7 is a sectional view of the direct clamp gripper of FIG. 4
and a knee implant, with clamp pads of the gripper positioned to clamp
the post;

[0019] FIG. 8 is a sectional view of the direct clamp gripper of FIG. 4
and a knee implant, with the clamp pads of the gripper positioned to
release the post;

[0020] FIG. 9 is a perspective view of a part regrip fixture according to
the principles of the present disclosure clamping notches in a knee
implant;

[0021] FIG. 10 is a side view of a knee implant being transferred between
the direct clamp gripper of FIG. 4 and the part regrip fixture of FIG. 9;

[0022] FIG. 11 is a sectional view of the part regrip fixture of FIG. 9
and a knee implant, with tabs of the regrip fixture positioned to engage
the notches;

[0023] FIG. 12 is a sectional view of the part regrip fixture of FIG. 9
and a knee implant, with tabs of the regrip fixture positioned to release
the notches; and

[0024] FIG. 13 is a perspective view of a direct clamp gripper according
to the principles of the present disclosure clamping a post of a knee
implant.

[0025] Corresponding reference numerals indicate corresponding parts
throughout the several views of the drawings.

DETAILED DESCRIPTION

[0026] Example embodiments will now be described more fully with reference
to the accompanying drawings.

[0027] Referring now to FIG. 1, a robotic finishing system 10 used for
finishing parts such as knee implants is illustrated. The system 10
includes a part staging fixture 12, a robot 14, a direct clamp gripper 16
coupled to the robot 14, a wheel finishing device 18, a belt finishing
device 20, and a part regrip fixture 22. The robot 14 may be a FANUC
M7101C 6-Axis robot with a 110-pound payload. The finishing devices 18,
20 may include 5 horsepower dual stacked buff heads or ultra-light front
floating heads. The system 10 may include more or less finishing devices.

[0028] In operation, the robot 14 picks up a knee implant from the part
staging fixture 12 and manipulates the implant relative to the finishing
devices 18, 20 to perform buffing, polishing, and the like. To expose all
surfaces of the implant to the finishing devices 18, 20, the robot 14
transfers the part to the regrip fixture 22 and regrips the part from an
opposite side. Finishing operations are then continued.

[0029] Referring now to FIG. 2, the staging fixture 12 may support a knee
implant 24 both before and after the implant 24 is finished in the system
10. Although a knee implant is used throughout this description as an
example of the part to be finished, the present disclosure is not limited
to tooling for finishing knee implants.

[0030] The staging fixture 12 includes a mounting base block 26, a support
block 28, a part nesting block 30, and an actuator 32. The mounting base
block 26 includes holes 34 in which fasteners may be inserted to fix the
staging fixture 12 to, for example, a bedplate. The blocks 26, 28 may
include holes (not shown) in which fasteners may be inserted to fix the
support block 28 to the mounting base block 26. The support block 28
includes mounting surfaces 36 on which the part nesting block 30 and the
actuator 32 are mounted. The mounting surfaces 36 may include holes (not
shown) in which fasteners may be inserted to mount the part nesting block
30 and the actuator 32 to the support block 28.

[0031] The part nesting block 30 includes a mounting portion 38 and an
engaging portion 40. The mounting portion 38 has a rectangular shape and
includes holes 42 in which fasteners may be inserted to mount the part
nesting block 30 to the support block 28. The engaging portion 40 has a
hexagonal shape providing outer surfaces 43. A clamp pad 44 is attached
to an end of the engaging portion 40 via fasteners inserted through holes
45 in the clamp pad 44. A proximity sensor 46 is attached to an outer
surface 47 of the engaging portion 40 via a sensor bracket 48. The
actuator 32 may be a compact pneumatic cylinder that is single acting
with a spring return or double acting with a compressed air return.

[0032] The implant 24 includes fingers or condyles 50 and a cruciate gap
52 disposed between and separating the condyles 50. The condyles 50
include inner surfaces 54, extraction notches 56 located at outboard
edges of the implant 24, and one or more protrusions 58 extending from
the inner surfaces 54 adjacent to the extraction notches 56. The outer
surfaces 43 of the part nesting block 30 are shaped to substantially
conform to the inner surfaces 54 of the implant 24. The protrusions 58
may be posts, as shown, that are integrally formed with the implant 24 or
threaded into holes (not shown) provided in the implant 24.
Alternatively, the protrusions 58 may be a single rectangular box
disposed between the condyles 50.

[0033] Referring now to FIG. 3, inner components of the staging fixture 12
will now be described. The inner components of the staging fixture 12
include a coupler or pushrod 60 and a clamp pad 62. The pushrod 60
couples the clamp pad 62 to the actuator 32. The pushrod 60 and the clamp
pad 62 are slideable within a bore 63 extending through the support block
28 and the part nesting block 30. The clamp pad 62 includes a clamp
surface 64 opposing a clamp surface 66 on the clamp pad 44.

[0034] Referring to FIGS. 2 and 3, operation of the staging fixture 12
will now be described. The staging fixture 12 engages the inner surfaces
54 of the implant 24 to locate the implant 24, and engages one of the
protrusions 58 on the implant 24 to grip the implant 24. The implant 24
may be loaded onto the staging fixture 12 and unloaded from the staging
fixture 12 either manually or using a gantry crane (not shown). The outer
surfaces 43 of the part nesting block 30 engage the inner surfaces 54 of
the implant 24 to locate the implant 24 relative to the staging fixture
12.

[0035] The staging fixture 12 grips the implant 24 by actuating the
pushrod 60 toward the clamp pad 44 to engage the clamp surfaces 64, 66 on
the clamp pads 44, 62 with one of the protrusions 58 on the implant 24.
The staging fixture 12 may grip the implant 24 when the proximity sensor
46 detects the presence of the implant 24. The staging fixture 12
releases the implant 24 by actuating the pushrod 60 away from the clamp
pad 44 to disengage the clamp surfaces 64, 66 from one of the protrusions
58.

[0036] Gripping components and operation of the staging fixture 12 may be
identical to those of the gripper 16 or similar to those of the gripper
16 with only minor differences such as sizing. The gripping components of
the staging fixture 12 may be sized smaller than the gripping components
of the gripper 16, as the staging fixture 12 need not be able to
withstand high loads exerted on the implant 24 during finishing. In view
of the foregoing, the discussion below regarding the gripping components
and operation of the gripper 16 also applies to the staging fixture 12.

[0037] Referring to FIGS. 4 through 6, the gripper 16 includes a first
adapter 68, an actuator 70, a second adapter 72, dowel pins 74, a spacer
block 76, a support 78, clamp pads 80, 82, and cover plates 83. The clamp
pads 80, 82 include clamp surfaces 84, 86, respectively, that are shaped
to substantially conform to the contour of the protrusions 58 of the
implant 24. Minor differences between the clamp surfaces 84, 86 and the
perimeter surfaces of the protrusions 58 may be allowed for ease of
manufacture. For example, the perimeter surfaces of the protrusions 58
may taper inward toward the respective ends of the protrusions 58, while
the clamp surfaces 84, 86 may be straight.

[0038] The first adapter 68 may be a cylindrical plate having a bore 87
extending through the first adapter 68 and may include holes 88, 90, and
92 extending at least partially through the first adapter 68. The holes
88, 90, and 92 may be threaded, unthreaded, straight, countersunk, and/or
counterbored depending on the fastener type to be inserted therein.
Fasteners 94 are inserted into the holes 88 to couple the gripper 16 to
the robot 14 of FIG. 1. The fasteners 94 may be socket head screws, as
shown, and the holes 88 may be counterbored.

[0039] The actuator 70 may be a single or double acting compact pneumatic
cylinder having a rectangular block shape and including a piston 96
therein. The piston 96 includes a shaft 98 including a threaded hole 100
therein. The actuator 70 further includes a bore 102 extending partially
through the actuator 70 and holes 104 for fixing the actuator 70. The
piston 96 is slideable within the bore 102, and travel of the piston 96
may be limited by the housing of the actuator 70. The holes 104 may be
through holes.

[0040] The second adapter 72 may be a rectangular plate including a bore
106 and holes 107, 108, 109, and 110 extending at least partially through
the second adapter 72. Fasteners 112 are inserted into the holes 92, 104,
and 108 to couple the second adapter 72 and the actuator 70 to the first
adapter 68. The fasteners 112 may be socket head screws, as shown, and
the holes 108 may be counterbored through holes receiving the socket head
screws. Dowel pins 74 are inserted into holes 110 and 90.

[0041] The spacer block 76 includes a bore 114 and holes 116, 118
extending at least partially through the spacer block 76. The holes 116
may be unthreaded. Dowel pins 120 are inserted into the holes 116 to
align the bore 114 relative to the bores 102 and 106. A coupler or
pushrod 122 is slideable within the bore 114 and couples end clamping
components of the gripper 16 to the piston 96. The pushrod 122 includes a
shaft 124 and a flat surface 126 including holes 128, 130 for receiving
fasteners such as screws and pins. The shaft 124 of the pushrod 122 is
threaded into the hole 100 of the piston 96, and a nut 132 is threaded
onto the pushrod 122 to prevent the shaft 124 from backing out of the
hole 100. The nut 132 may be a hex jam nut, as shown.

[0042] The support 78 may include a mounting portion 133 including holes
134 and an engaging portion 135 including an opening 136, holes 138,
holes 140, and an enclosed end 139 including holes 140, and outer
surfaces 142. The opening 136 exposes or provides access to the clamp
surfaces 84, 86 of the clamp pads 80, 82. The engaging portion 135 may
have an octagonal shape providing the outer surfaces 142 of the engaging
portion 135 such that the outer surfaces 142 are shaped to substantially
conform to the inner surfaces of the implant 24. The outer surfaces 142
may include a horizontal surface that is horizontal relative to ground,
an angled surface that is oriented at a reflex angle relative to the
horizontal surface, and a side surface that is oriented at a right angle
relative to the horizontal surface.

[0043] Fasteners 144, such as screws, are inserted into holes 145 in the
clamp pads 80 and into the holes 128 in the pushrod 122 to attach the
clamp pads 80 to the pushrod 122. When assembled, the surfaces of the
clamp pads 80 receiving the fasteners 144 may be recessed relative to the
outer surfaces 142 of the support 78 to avoid contacting the implant 24
as the clamp pads 80 are actuated within the opening 136. Dowel pins 146
are inserted into holes 147 in the clamp pads 80 and into the holes 130
in the pushrod 122 to position the clamp pads 80 relative to the pushrod
122. Fasteners 148, such as screws, attach the cover plates 83 to the
support 78. The cover plates 83 may cover a portion of the opening 136
that does not need to be accessible after the clamp pads 80, 82 are
assembled.

[0044] Fasteners 150 are inserted into the holes 140 in the enclosed end
139 of the support 78 and into holes 153 in the clamp pads 82 to attach
the clamp pads 82 to the support 78. The fasteners 150 may be screws, as
shown, the holes 140 may be unthreaded, and the holes 153 may be
threaded. Fasteners 152 are inserted into the holes 109, 118, and 134 to
attach the spacer 76 and the support 78 to the second adapter 72. The
fasteners 152 may be socket head screws, as shown, and may be used in
conjunction with washers 154.

[0045] Referring now to FIGS. 7 and 8, inner detail of the gripper 16 is
illustrated. The actuator 70 includes a cavity 156 to which the bore 102
extends. Travel of the piston 96 may be limited due to contact between
the head of the piston 96 and the cavity 156. The support 78 includes
bores 158, 160 and a bushing 162. The bore 158 may have a greater
diameter than the bore 160 to accommodate the bushing 162. The pushrod
122 slides within the bore 160 and the bushing 162.

[0046] Referring again to FIGS. 4 through 8, operation of the gripper 16
will now be discussed. The gripper 16 engages the inner surfaces 54 of
the implant 24 and clamps one of the protrusions 58 on the implant 24 to
hold the implant 24 during finishing. Engaging the inner surfaces 54 of
the implant 24 locates the implant 24 relative to the gripper 16 and
facilitates clamping only one of the protrusions 58 by reducing stress
levels in the implant 24 during finishing. Clamping only one of the
protrusions 58 avoids the need to extend the part nesting block 30 across
the cruiciate gap 52 of the implant 24 when the gripper 16 clamps the
implant 24, enabling automated finishing of the cruciate gap 52.

[0047] When gripping the implant 24, the robot 14 of FIG. 1 positions the
clamp pads 80, 84 of gripper 16 on opposite sides of one of the
protrusions 58 of the implant 24. The portion of the gripper 16 that
engages the implant 24, including the outer surfaces 142 of the part
nesting block 30, are symmetric about a longitudinal mid-plane extending
through the gripper 16. This enables the gripper 16 to clamp either of
the protrusions 58 on the implant 24, as shown in FIGS. 4 and 5, without
being rotated to engage the outer surfaces 142 of the part nesting block
30 with the inner surfaces 54 of the implant 24. In turn, the robot 14
does not need the ability to rotate the gripper 16, which may reduce
costs associated with the robot 14.

[0048] When the clamp pads 80, 82 are positioned on opposite sides of one
of the protrusions 58 on the implant 24, the actuator 70 actuates the
piston 96 to move the pushrod 122 and the clamp pad 80 toward the clamp
pad 82. Travel of the piston 96, the pushrod 122, and the clamp pad 80 in
this direction is stopped when the clamp surfaces 84, 86 of the clamp
pads 80, 82 engage the protrusions 58, as shown in FIG. 7. The actuator
70 holds the clamp pad 80 in this position to hold the implant 24 in the
gripper 16. When the clamp pads 80, 82 are not positioned about an
object, travel of the piston 96, the pushrod 122, and the clamp pad 80 in
this direction is limited by contact between the clamp pads 80, 82.

[0049] When releasing the implant 24, the actuator 70 actuates the piston
96 to move the pushrod 122 and the clamp pad 80 away from the clamp pad
82. Travel of the piston 96, the pushrod 122, and the clamp pad 80 in
this direction is limited by contact between the head of the piston 96
and the bottom of the cavity 156 in the actuator 70, as shown in FIG. 8.
However, the actuator 70 may stop travel in this direction prior to
encountering this limit.

[0050] The amount by which the clamp pads 80, 82 may be separated to
accommodate various protrusions 58 on the implant 24 is governed by the
travel limit in the releasing direction. However, the clamp pads 80, 82
may be shaped and sized to conform to the shapes and sizes of the
protrusions 58 on the implant 24. In addition, the depth to which the
pushrod 122 is threaded in the piston 96 may be adjusted to accommodate
protrusions 58 having various shapes and sizes.

[0051] Since the clamp pads 80, 82 may be detached from the pushrod 122,
the clamp pads 80, 82 may be replaced with clamp pads having different
shapes or sizes to accommodate the protrusions 58 when gripping or
releasing. In addition, the clamp pads 80, 82 may be replaced as the
clamp surfaces 84, 86 on the clamp pads 80, 82 wear out. Replacing the
clamp pads 80, 82 and/or varying the threaded depth of the pushrod 122 in
the piston 96 to accommodate the protrusions 58 may save costs relative
to other modifications to the gripper 16.

[0052] Referring to FIG. 9, the regrip fixture 22 includes a base block
164, an actuator 166, adapters 168, and fingers 170. The base block 164
may includes holes, such as those shown, in which fasteners may be
inserted to fix the base block 164 to, for example, a bedplate. The
actuator 166 includes slide tracks 172 to which the adapters 168 attach.
The adapters 168 may be attached to the tracks 172 using fasteners, such
as the socket head screws shown. The fingers 170 include tabs 174 and are
attached to the adapters 168. The fingers 170 may be attached to the
adapters 168 using fasteners, such as socket head screws. The tabs 174
are shaped and sized to be inserted into and engage the notches 56 in the
implant 24.

[0053] With additional reference to FIGS. 10 through 12, operation of the
regrip fixture 22 will now be discussed. The regrip fixture 22 holds the
implant 24 by the notches 56 in the implant 24 while the robot 14
switches from holding one of the protrusions 58 to holding another one of
the protrusions 58. To enable the regrip fixture 22 to grip the implant
24, the robot 14 positions the notches 56 in the implant 24 adjacent to
the tabs 174 of the fingers 170, as shown in FIG. 10.

[0054] When gripping the implant 24, the regrip fixture 22 actuates the
adapters 168 and the fingers 170 along the length of the track 172 to
move the tabs 174 on the fingers 170 toward the notches 56 in the implant
24. The regrip fixture 22 stops actuating the tabs 174 in this direction
when the tabs 174 bottom out in the notches 56, as shown in FIG. 11. In
this position, the engagement between the tabs 174 on the fingers 170 and
the notches 56 in the implant 24 holds the implant 24. While the regrip
fixture 22 holds the implant 24, the robot 14 moves to the opposite side
of the implant 24 to grab another one of the protrusions 58 on the
implant 24.

[0055] When releasing the implant 24, the regrip fixture 22 actuates the
adapters 168 and the fingers 170 along the length of the track 172 to
move the tabs 174 on the fingers 170 away from the notches 56 in the
implant 24. The regrip fixture 22 stops actuating the tabs 174 in this
direction when the tabs 174 are removed from the notches 56, as shown in
FIG. 12. Travel in this direction is limited by the travel limits of the
actuator 166. However, the adapters 168 and/or the fingers 170 may be
modified to accommodate various implant shapes and sizes.

[0056] Referring now to FIG. 13, a direct clamp gripper 16' is
substantially similar to the direct clamp gripper 16 such that only
differences between the grippers 16, 16' will now be discussed. In
contrast to the gripper 16, the portion of the gripper 16' that engages
the implant 24 is not symmetric about a longitudinal mid-plane extending
through the gripper 16'. Thus, the gripper 16' must be rotated as the
gripper 16' transitions between clamping the protrusions 58 on the
implant 24. However, the gripper 16' may require less material and less
machining operations as compared to the gripper 16, thereby saving costs
associated with the gripper 16'.

[0057] The gripper 16' includes an engaging portion 175 including a flat
surface 176, an opening 177, and an enclosed end 178. The engaging
portion 175 has a hexagonal shape rather than the octagonal shape of the
engaging portion 135 of FIG. 6. The flat surface 176 extends between two
of the surfaces 142' shown as parallel and vertical in FIG. 13, and the
flat surface 176 is opposite one of the surfaces 142' shown as horizontal
in FIG. 13. The flat surface 176 may be positioned in the vertical
direction of FIG. 13 such that the height of the two parallel surfaces
142' is equal to the height of the two corresponding surfaces 142 of FIG.
6. The opening 177 extends only partially through the engaging portion
175, as the opening 177 does not extend through the flat surface 176. The
enclosed end 178 includes holes 180 that are in different positions
relative to the holes 140 in the enclosed end 139 of FIG. 6. This
difference in the positions of the holes 140, 180 is due to the geometric
differences between the engaging portions 135, 175.

[0058] The foregoing description of the embodiments has been provided for
purposes of illustration and description. It is not intended to be
exhaustive or to limit the invention. Individual elements or features of
a particular embodiment are generally not limited to that particular
embodiment, but, where applicable, are interchangeable and can be used in
a selected embodiment, even if not specifically shown or described. The
same may also be varied in many ways. Such variations are not to be
regarded as a departure from the invention, and all such modifications
are intended to be included within the scope of the invention.